1. Field of the Invention
The present invention relates to fluorescent lamp operating circuits and, more particularly, to an electronic fluorescent lamp operating circuit for starting and operating a fluorescent lamp load at a controllable output level.
2. Description of the Prior Art
Presently, fluorescent lamp operating circuits for providing variable illumination levels from fluorescent lamps have involved the use of chopping circuitry to limit the overall electrical power delivered to the fluorescent lamp. Such circuits employ high frequency signals during a portion of the a-c power wave, which create electromagnetic interference having a deleterious effect upon the operation of electronic equipment located in the vicinity of the ballast circuit or lamps and low power factor. The prior art fluorescent lamp control circuits provided dimming of the level of illumination by dissipating the energy within the power supply circuitry. This created heat which had to be dissipated from the system and resulted in substantial inefficiencies in terms of light output versus electrical power input.